Disc assemblies are known in the art and are often used in connection with clutch assemblies and brake assemblies. One use of disc assemblies are as clutch assemblies in automatic transmissions.
In a shifting operation of an automatic transmission, mating plates are utilized with the disc assemblies. In most automatic transmission uses, the disc assemblies must be lubricated. The prior art disc assemblies often include core plates which are covered with a friction layer or friction facing. Because of the paper-type structure of the facing, poor heat conduction often results during shifting. This can sometimes be compensated for by the absorption of oil into the pores of the facing during open clutch operation. During the closing of the clutch operation, the evaporation of oil often results in a temperature drop.
In order to obtain the desired cooling, it is known in the prior art to groove the outer linings or facings. The grooves are used as passageways in an oil cooling system. The oil volume flowing through the disc assembly prevents damage to the linings, seals and to the overall clutch assemblies. A grooved friction lining or facing is disclosed in U.S. Pat. No. 4,878,282 granted Nov. 7, 1989.